Pollution• An undesirable and unfavorable change in

physical, chemical and biological characteristics of land air and water that harmfully affect both plant and animal life including that of man.

• Caused mainly by population growth, urbanization and technological advances.

• Things that cause pollution are called pollutants

1. Solid wastes (sewage, soot dust etc. )2. Gases (carbon dioxide, carbon monoxide, nitrogen dioxide etc.)

3. Industrial wastes (acids, alkalies)

4. Agricultures pollutants (pesticides, herbicides)

5. Metals (Iron, Zinc, Mercury)

6. Radioactive substances7. Oil

Main pollutants

Two Types of Pollutants

• Biodegradable pollutants: Those which are rapidly decomposed by natural processes. Eg. Domestic sewage

• Non-degradable pollutants: That degrade very slowly into natural environment. Eg. Plastic, aluminum cans, glass, DDT, mercuric salts etc.

• Classification based on environment: 1. Atmospheric pollution

2. Water pollution

3. Soil pollution• Classification based on nature of pollutants

1. Chemical pollution

2. Noise pollution

3. Pollution by radio activity.

Atmospheric pollution• Contamination of atmospheric air due to

accumulation of harmful or toxic materials

1. Natural sources.1. Volcanic eruption2. Forest fire3. Decaying organic matter4. Sand storms

2. Man made pollutants Only 0.05% of total atmospheric pollutants.

Caused by the outputs of industries and automobiles

• Gaseous pollutants: 1. Carbon monoxide.2. nitrogen oxide, 3. sulphur dioxide etc.

• Particulate substances• Solid and liquid particles1.Large particles that easily settle down in air.

(sand and water drops)2.Fine paricles that float in air for long time

(dust and mist).3.Finer particles that never settle (smoke,

aerosol and fumes)

• Primary pollutants• Those emanating from a source

• Eg. Carbon monoxide, nitrous oxides etc.

• Secondary pollutants

• Produced by combustions of primary pollutants in atmosphere

• Eg. Atmospheric reactions of hydro-carbons and nitrous oxide, peroxy acetyl nitrate

Sources of Air Pollution

• Stationary combustion sources: Combustion of coal and petroleum produces

CO,SO2,various Nitrogen compounds and fly ash containing trace metals like arsenic, lead and Mercury.

Incomplete burning of petroleum produces soot and other toxic gases.

Oxides of sulphur react with atmosphere producing sulphuric acid which forms acid rain or acid precipitation.

• Mobile combustion sources• Automobile is a major source of pollution• Their exhaust contain carbon

monoxide(77.2%), Oxides of nitrogen(7.7%) and hydrocarbons(13.7%)

• Photochemical reactions on Oxides of nitrogen and hydrocarbons produce photochemical smog which contains Peroxy acetyl nitrate and Ozone.

• Tetra ethyl lead in petroleum produces various lead compounds.

• Industrial processing and other sources

• Smoke from factories

• Compounds contain Chorine and Fluorine used in propellants, refrigerants and in aerosol can produce toxic outputs

• Solvents in spray painting. Dyeing, printing etc.

• Blasting, drilling, crushing, mixing etc.

Effects of air pollution

• Human health– Allergic reaction and bronchial asthma– Co is respiratory poison– NO impairs functioning of lungs

– SO2 penetrates tissues and causes mouth drying

– Hydrocarbons and soot are carcinogenic

• Damage to vegetation

• Injury to animals

• Deterioration of materials

• Aesthetic insults

• Change in climate

Other effects

Control Measures

– Removal of pollutants

– Conversion of pollutants into harmful materials

– Reduce sulphur content before burning

– Use of energy sources other than fossil fuels

– Legal measures from authorities

– Increased planting of vegetation

Water Pollution– Contamination of water by addition of

undesirable organic, inorganic or biological substances to water sources

– Natural sources: soil erosion, leaching of minerals from of rocks and decay matter.

– Industrial effluents

– Destroys ecosystem and effects human health

Sources of water pollution

• Community waste waters

• Industrial wastes

• Agricultural sources

• Thermal pollution

• Under ground water pollution

• Marine pollution

Effects of water pollution• Mercury poisoning causes Mina Mata disease in

man.• Inorganic nitrates promote excessive plant

growth in lakes and reservoirs• Pesticides are harmful to aquatic life • Organocholrines pass through food chain to

animals and is harmful• Dyes and inorganic compounds induce colour

change in animals• .

• Increased turbidity due to suspended particles.

• Unpleasant odours and bad taste

• Soaps and alkalies cause foam formation

• Eutrophication provides rich growth of micro organisms that consume dissolved oxygen

• Thermal pollution cause damage to aquatic life

Control of water pollution

• Treatment of garbage and sewage.

• Extraction of useful substances.

• Chemical treatment.

• Reduction of temperature of waste water.

• Minimize the use of non - degradable pesticides.

• Proper enactment of laws by government.

Soil pollution

• Undesirable change in the physical, chemical or biological property which adversely affects its productivity

• Caused by dumping of wastes, agrochemicals and as indirect result of air pollution

Sources of Soil Pollution

• Domestic wastes

• Agricultural wastes

• Industrial wastes

• Excretory products

• Salination

Control of soil pollution

• Proper disposal of industrial and agricultural wastes

• Recycling and recovery of materials

• Minimize the manufacture and use of chemical fertilizers

• Reduce the use of pesticides

Land degradation

• The productivity of soil is going down. The main reasons are

• Soil erosion

• Shifting cultivation

• Desertification

• Developmental activities

Control measures• Control soil erosion and floods by restoring

forest and grass cover to the soil

• Crop rotation and mixed crops

• Improved drainage facilities to prevent salinity

• Mulching to prevent sand shifting.

• Belt of trees as wind breakers

Radio active pollution

• Physical pollution that affects air, water and soil. Caused by ionizing radiations of harmful nature emitted from disintegrating atomic nuclei.

• The natural sources include cosmic rays that reaches the earth surface and radiations from radium 224, uranium 235 thorium 232 etc

Man made sources• Nuclear weapons

• Reactors and Nuclear fuel

• Radioactive isotopes used for scientific research( carbon 14 iodine 125 etc.)

• Waste waters containing these wastes

• X-rays used in medical practices• Ultra violet rays present in solar

radiations

Effects• Depolymerization of DNA

• Denaturation of proteins

• Induce mutations and cancer

• Radioactive substances in food chain cause retarded growth, leukemia and bone cancer.

• Causes sterility

• Increases infant mortality rate

Control measures• Prevention of leakage of radioactive

elements from nuclear reactors.• Proper storage and disposal of nuclear

wastes• Regular monitoring and high risk analysis• Increasing the use of non harmful energy

sources• Global understanding about nuclear

explotions

Noise pollution• Unwanted high pitch sound that pollutes

the environment.

• Maximum tolerable intensity of sound is 85 decibels

• The main sources are automobiles, aero planes, loudspeakers, industries and other electro-mechanical devices.

Effects of noise pollution

• Damage to ear drum and impairment to hearing.

• Damages heart, liver and brain

• Emotional disturbances and behavioral changes

• Leads to anxiety and stress

Control measures• Design machines with minimum sound

• Proper lubrication maintenance of machines and installation of silencers.

• Use of sound absorbing materials

• Use of noise protective devices

• Acoustic Zoning.

• Keep plenty of vegetation proper enforcement of legal measures.